<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    body {
        margin: 0;
    }

    .header {
        position: relative;
        z-index: 1000;
        width: 100%;
        height: 60px;
        background: #FD5;
    }

    .box {
        width: 300px;
        height: 200px;
        margin: 0 auto;
        background-color: orange;
        box-shadow: 0 0 30px #000;
        /* 兼容样式 */
        -webkit-box-shadow: 0 0 30px #000;
        -moz-box-shadow: 0 0 30px #000;
        -o-box-shadow: 0 0 30px #000;
    }
</style>

<body>
    <div class="header"></div>
    <div class="box"></div>
</body>
<script></script>

</html>